The invention comprises a tolerance compensating mounting device comprising a bushing having an internal and external thread. The bushing is threaded into a part to be mounted to a surface. A bolt is then threaded into a bushing bore using the internal threads. The internal threads cause an interference fit between the bolt shank and the threads, temporarily preventing further insertion of the bolt. The bolt is then turned further, thereby turning the bushing and causing the bushing to unscrew from the part toward the mounting surface until the bushing seats on the mounting surface, thereby completely compensating for a tolerance gap. As the bolt is turned further, at a relatively low torque the sacrificial internal threads are stripped allowing the bolt to be fully torqued into the mounting surface hole, thereby simultaneously connecting the components with a properly torqued connection while compensating for a tolerance gap.
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16. A device comprising:
a substantially cylindrical body having a thread on an external surface and describing an internal bore for receiving a fastener;
a first surface extending substantially perpendicularly to a major axis at one end of the cylindrical body; and
the internal bore having a sacrificial thread for engaging a fastener.
12. A mounting bushing comprising:
a substantially cylindrical body having a thread on an external surface for engaging a part and describing an internal bore for receiving a fastoner, the body further comprises symmetrically arranged engagement surfaces parallel to a major axis for turning the body;
a first surface extending substantially perpendicularly to a major axis at one end of the cylindrical body for engaging a mounting surface;
the internal bore having a surface feature comprising a sacrificial thread that deforms upon engaging a non-threaded fastener portion.
1. A device comprising:
a substantially cylindrical body having a thread on an external surface and describing an internal bore for receiving a fastener, the bore parallel to a major axis;
the internal bore having a surface feature engagable with the fastener, the surface feature comprising a sacrificial thread which deforms upon engagement with a non-threaded fastener portion;
a first surface extending substantially perpendicularly to a major axis at one end of the cylindrical body; and
the body further comprises symmetrically arranged engagement surfaces parallel to a major axis for turning the body.
13. A tolerance compensating device comprising:
a bushing having a helical thread on an external surface for engaging a cooperating helical thread on a structural part and further describing a bore for receiving a fastener, rotation of the bushing in the structural part determining an axial position of the bushing;
a bushing surface for engaging another structural part;
a fastener having a non-threaded fastener shank; and
a member engaged with the fastener shank and with a bore surface, rotation of the fastener causing a rotation of the member and thereby of the bushing into a bearing position on the other structural part.
10. A mounting bushing comprising:
a fastener;
a substantially cylindrical body having a thread on an external surface for engaging a part and describing an internal bore for receiving the fastener, the bore parallell to a major axis, the body further comprises symmetrically arranged engagement surfaces parallel to a major axis for turning the body;
a first surface extending substantially perpendicularly to a major axis at one end of the cylindricai body for engaging a mounting surface;
the internal bore having a surface feature on a portion of the internal bore, the surface feature comprising a sacrificial thread having a diameter less than an internal bore diameter for engaging a fastener, the fastener further engageable with a mounting surface hole;
wherein the fastener further comprises a second surface extending perpendicularly to a fastener major axis for engaging a part.
2. The device as in
the threaded fastener is engageable with a mounting surface hole.
3. The device as in
4. The device as in
the internal bore surface further comprises a feature having threads for engaging a fastener.
5. The device as in
the external thread is opposite hand from the thread on the internal bore surface.
9. The device as in
15. The device as in
17. The device as in
the thread on the external surface opposite hand from the sacrificial thread.
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This application is a continuation-in-part of and claims priority from U.S. application Ser. No. 09/840,265 filed Apr. 23, 2001, now abandoned.
The invention relates to a fastening device, and more particularly, to a tolerance compensating mounting device used to connect components while compensating for a fit tolerance between the components.
Assembly of equipment components can be adversely affected by tolerances, that is, dimensional differences between components that may result in gaps at fastening points. They cannot always be eliminated, but only allowed for in the assembled device. Tolerances can also “stack” when more than two components are joined at a particular location, creating a significant dimensional deviation or gap.
Tolerances may be very small, fractions of a millimeter, or very large, several millimeters, depending upon the circumstances. Larger tolerances generally reduce manufacturing costs.
Attempts have been made in the prior art to eliminate tolerances or to compensate for them in an assembled device. These generally comprise shims or screw type devices that fill the gap between the mating surfaces of the components to be joined. The shims or screw type devices are generally a separate component from the fasteners.
Representative of the art is U.S. Pat. No. 4,682,906 (1987) to Ruckert et al. which discloses a device for the clamping connection of structural parts which are spaced apart from each other by means of a spacer disk arranged within said space and resting by its outer broad side against one structural part.
Also representative of the prior art is U.S. Pat. No. 5,501,122 to Leicht et al. which discloses a twin cone device for aligning holes in components to be joined. The device comprises a set of conical structures joined by a bolt.
The prior art does not solve the problem of compensating for tolerances between planar mounting surfaces while simultaneously joining the components in a properly torqued or clamped manner; all without inducing undesirable stresses in the components. Nor does the prior art allow a component having non-coplanar connecting surfaces to be properly joined. Nor does the prior art provide a fastener that automatically compensates for a tolerance gap or clearance between mounting surfaces as part of the assembly process.
What is needed is a device that completely spans a clearance or tolerance gap between components to be joined using a threaded bushing while simultaneously connecting the components. What is needed is a device that completely spans a tolerance gap between components to be joined using a threaded fastener. What is needed is a device that automatically compensates for a tolerance gap during installation. The present invention meets these needs.
The primary aspect of the invention is to provide a tolerance compensating mounting device that completely compensates for a tolerance gap or assembly clearance between components to be joined using a threaded bushing while simultaneously connecting the components.
Another aspect of the invention is to provide a tolerance compensating mounting device that completely compensates for a tolerance gap between components to be joined using a threaded fastener.
Other aspects of the invention will be pointed out or made obvious by the following description of the invention and the accompanying drawings.
The invention comprises a tolerance compensating mounting device comprising a bushing having an internal and external thread. The bushing is threaded into a part to be mounted to a surface. A bolt is then threaded into a bushing bore using the internal threads. The internal threads cause an interference fit between the bolt shank and the threads, temporarily preventing further insertion of the bolt. The bolt is then turned, thereby turning the bushing and causing the bushing to unscrew from the part toward the mounting surface until the bushing bears upon the mounting surface, thereby completely compensating for a tolerance gap. As the bolt is turned further, the sacrificial internal threads are stripped to allow the bolt to be fully torqued into the mounting surface hole, thereby simultaneously connecting the components while compensating for a tolerance gap.
The accompanying drawings, which are incorporated in and form a part of the specification, illustrate preferred embodiments of the present invention, and together with a description, serve to explain the principles of the invention.
Thread 102 comprises approximately two pitches of any thread form known in the art. Bushing 101 also comprises bore or hole 103 that runs the length of bushing 101 along a major axis. Bolt 200 engages bushing 101 through hole 103. Bolt 200, see
Bushing 101 comprises a metallic material on the preferred embodiment. However, one can appreciate that it may also comprise a non-metallic material, for example a composite, ceramic or plastic, for use in situations where a non-conductive insulator is required between joined parts, or in the case where a low-torque application is required.
Bushing 101 also comprises an external surface having external threads 104. Threads 104 extend along a length L of an outer surface of bushing 101.
Bushing 101 further comprises symmetric flats 105 that are parallel to a major axis allowing use of a wrench or fingers to install the tool, see FIG. 2 and FIG. 3. The flats are of a shape similar to that of a nut or bolt head, known in the art. The flats may also be replaced with a knurled surface or plain cylinder surface to allow the bushing to be turned by hand, i.e., finger.
Referring to
Part P is then aligned with mounting surface M such that bolt 200 lines up with hole MH.
In an alternate embodiment an adhesive, such as Loctite 2015™, is applied to bolt threads 202. The adhesive is used to temporarily adhere bolt threads 202 to threads 102. In this embodiment, bushing 101 is first inserted into part P as described above. A portion of bolt threads 202 are coated with the adhesive. Bolt 200 is threaded into the bush and thereby into threads 102. The adhesive temporarily fastens the bolt threads 202 to bush threads 102. Bolt 200 is then turned which causes bushing 101 to turn as well. Bolt 200 is turned until surface 107 engages mounting surface M, at which point bushing 101 stops turning. The adhesive then fails in shear upon further application of torque to the bolt, whereby the bolt continues to turn until it is fully engaged with a hole MH.
Referring to
A further embodiment may comprise a variation of thread 102 where one thread is slightly distorted so that the thread is slightly “stiff” causing a frictional engagement with the bolt threads 202.
One can also appreciate that the threads on bolt 200 which engage threads 102 partially or fully deform or strip once bushing 101 is seated on the mounting surface, because the upper portion of the bolt threads are not expected to engage the threads in mouting hole MH.
In an alternate embodiment, diameter D1 of bolt 200, see
The application of a torque to the bolt 200 to strip the threads 102 also has the effect of placing a preload on part P. This feature of the invention has the benefit of stiffening the part and overall assembly. The magnitude of the preload can be adjusted according to the torque required to strip threads 102.
Once bushing surface 107 engages mounting surface M, a torque is applied to the bolt, causing sacrificial threads 102 to fail. Bolt 200 is then fully threaded into threaded hole MH in mounting surface M until bolt flange 201 engages a bearing surface of part P. Bolt 200 may then be torqued to an appropriate torque value depending upon the application. As one can see, the tolerance gap has been automatically and completely spanned with the bushing.
As can be seen in FIG. 4 and
The inventive tool can be used to eliminate the effect of tolerance stacks (or, indeed, to allow the use of wide tolerances) in a number of instances, for example, in the case where a large clearance is needed to allow easy assembly of a component while fully compensating for the tolerance. The inventive device can also be used to compensate for tolerances when bolting between faces in different planes as well as bolting to faces at odd angles to a primary surface mounting surface.
Also note that the inventive device can be “inverted” in an alternate embodiment.
Once bushing 101 and part P are seated against surface 108, threads 102 are stripped as described above and bolt 200 is then completely torqued down.
In yet another alternate embodiment, threads 102 extend along the length of bore 103 and are not sacrificial. Threads 102 are the opposite hand from the threads 104. In this embodiment, bushing 101 is first threaded into mounting hole MH using left-hand threads 104. Bolt 200 is then inserted through a hole PH in part P and into bore 103. In this embodiment, part P has no threads in the hole, nor does bolt 200 threadably engage the mounting surface hole. As the bushing 101 is unscrewed from the mounting surface M by turning action of bolt 200, bushing surface 108 comes into engagement with part P.
Bolt 200 is then fully screwed into bushing 101. The left-hand thread 104 engages mouting hole MH while bolt 200 is fully torqued in place. One can appreciate that it is desireable that a minimum number of full threads engage the hole MH to develop the full strength of the connection, as known in the art of threaded connections.
One skilled in the art can also appreciate that the bushing 101 can be rotated by hand or by means of a tool or wrench using flats 105, either for installing it into a part or turning it to compensate for a tolerance clearance T.
In use, once bushing 101 is inserted in to part P, bolt 200 is pressed into hole 103 until splines 2000 come into contact with shoulder 1000. Bolt 200 is further pressed axially into hole 103 with sufficient force to cause splines 2000 to partially cut into shoulder 1000. Once splines 2000 are engaged with shoulder 1000 in this manner, bushing 101 is turned by turning bolt 200. Bushing 101 stops turning when surface 107 engages M. As further torque is applied to bolt 200, splines 2000 shear off thereby allowing bolt 200 to be fully threaded into M, and thereby fully engage P as shown in FIG. 5.
Splines 2000 have a somewhat conical form, being disposed at an angle α to a bolt centerline A—A. Angle α allows splines 2000 to progressively engage shoulder 1000 up to a predetermined point without allowing splines 2000 to be driven completely past shoulder 1000 upon the initial engagement described in FIG. 10.
An outer diameter of threads 202 is less than an inner diameter of shoulder 1000 in order to prevent threads 202 from coming in contact with shoulder 1000 during insertion of bolt 200. This also provides enhanced X-Y movement flexibility of blot 200 to thereby enhance an alignment characteristic with hole MH.
In use, collar 500 is turned or threaded onto threads 202, which may include contact with shank edge 203. Contact with shank edge 203 limits any further travel of collar 500 up the bolt. Bolt 200 with collar 500 is then inserted into bore 103. An outside diameter of collar 500 is equal to or slightly greater than an inside diameter of bore 103 in order to create a frictional engagement between outer surface 501 of collar 500 and the inside surface 108 of bushing 101. As bolt 200 is turned into hole MH the frictional engagement of collar outer surface 501 with the inner surface 108 of bushing 101 causes bushing 101 to turn. As bushing 101 turns, bushing 101 moves axially resulting in surface 107 coming into contact with mounting surface M. Bushing 100 then stops turning as bolt 200 is then fully threaded into mounting hole MH. Once bushing 101 engages mounting surface M, collar 500 simply slides along inner surface 108. The sense or direction of threads 104 is the same as for threads 202. Threads 104 and 202 may either be right-handed or left-handed.
Collar 500 may comprise any material which can be cut by threads 202 and have a sufficient coefficient of friction on outer surface 501 to cause bushing 101 to turn upon a rotation of bolt 200. Collar 500 may comprise a plastic material, such as nylon, or any equivalent thereof.
Collar 500 may also comprise an inside diameter sufficiently small so as to create a frictional fit between collar 500 and bolt threads 202. A frictional fit is also present between outer surface 501 and inner surface 108 as described above. Such a frictional fit between the collar and the bolt threads does not require collar 500 to engage a shank edge 203 in order to cause bushing 101 to turn upon a rotation of bolt 200.
Although a form of the invention has been described herein, it will be obvious to those skilled in the art that variations may be made in the construction and relation of parts without departing from the spirit and scope of the invention described herein.
Stone, Roger, Knight, Brian Russell
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Executed on | Assignor | Assignee | Conveyance | Frame | Reel | Doc |
Oct 04 2002 | STONE, ROGER | GATES CORPORATION, THE | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 014514 | /0296 | |
Oct 04 2002 | KNIGHT, BRIAN RUSSELL | GATES CORPORATION, THE | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 014514 | /0296 | |
Oct 07 2002 | The Gates Corporation | (assignment on the face of the patent) | / |
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